Geological hydrogen deposits may point to an inexhaustible resource

Hydrogen is being hailed as a fuel of the future, but production requires large amounts of emission-free electricity, and some scientists say much of the hydrogen needed could come directly out of the ground.

Forsterite, an olivine mineral. Groundwater interacting with olivine can result in hydrogen building up in the surrounding rock layers. (Source: U.S. Geological Survey)

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Gold or white hydrogen is naturally produced in the Earth’s crust and, while it has still to be found and exploited in large quantities, scientists say the mechanisms by which it is created suggest potential global reserves could be enormous.

“The geology that you need to form hydrogen, and then trap it, are extremely pervasive across the world so, in theory, there are plenty of places we can go exploring for natural hydrogen,” says Owain Jackson, CEO and Co-Founder of H2Au.

If large deposits of readily created hydrogen could be exploited safely, much of the pressure of producing huge amounts of clean hydrogen would be reduced.

“The argument for natural hydrogen is extremely compelling,” says Jackson.

“It's a primary resource, you're not having to put energy in to get energy out as with manufactured hydrogen. So regardless of which color of hydrogen you’re creating, theoretically, natural hydrogen should always win on cost and effort.”

The team at H2Au (Au being the chemical symbol of gold) consists of what Jackson calls soft rock experts – from the oil and gas industry – and hard rock experts – from the mining industry.

“Oil and gas and mining have not traditionally worked together. They’ve not explored in the same areas or with the same datasets and so I think there is a little bit of a gap there.”

Massive potential

Reserves are potentially massive, Research Geologist at Central Energy Resources Science Center for the U.S. Geological Survey, Geoffrey Ellis says.

“The range of uncertainties are very large, from maybe thousands of megatons to billions of megatons … if you focus on the median value, it is in the order of tens of millions of megatons, and we tried to be conservative in the inputs that we used within a range of values that seemed reasonable,” Ellis says.

Collecting natural hydrogen may pose a similar problem to mining the gold known to exist in seawater, Ellis warns.

There is estimated to be around one gram of gold for every 100 million tons (MT) of seawater so collecting it would cost considerably more than the worth of the gold itself.

However, even cautious estimates suggest a vast untapped potential against forecast demand.

“The estimate right now is that, by the year 2050, they think that demand for hydrogen globally is going to be around 500 megatons per year. If we had 10 million megatons in the subsurface and we could just find 1% of that, and that 1% was shallow enough and findable, and we could produce that economically, that would meet all of those 500 megatons per year for 200 years,” he says.

Global hydrogen forecasts, propelled by the drive to decarbonize and move away from insecure fossil-fuel supply lines, needs to rise to 614 MT a year to reach 12% of energy demand by 2050, from around 75 MT a year today, according to the International Renewable Energy Agency (IRENA).

Map of hydrogen detections in various environments at concentrations of > 10% vol

(Click to Enlarge)

Source: 'The occurrence and geoscience of natural hydrogen: A comprehensive review.' By Viacheslav Zgonnik

Hidden and Untapped

For a long time, people believed that natural hydrogen did not exist on Earth since, being the lightest molecule, it easily seeps out of any container including, the theory stated, any rock formation in which it could be held.

It is also highly reactive, so would not be expected to accumulate in large quantities in the Earth’s crust.

Meanwhile, chromatography in the gas analyzers used in oil and gas drilling uses hydrogen as a carrier gas, so any hydrogen found during drilling was assumed to the part of baseline.

Global oil and gas exploration has not been looking for hydrogen and, consequently, has not found it.

However, natural occurrences of the gas have prompted scientists to adjust their exploration methods.

The most famous is the Flames of Chimaera, near Antalya in Turkey, where around a dozen active vents containing methane and between 7.5% and 11.3% hydrogen have been burning for more than 2,500 years.

The constantly burning fire is believed to be the origin of the first Olympic flame.

Striking gold in Mali

While the Flames of Chimaera suggested the subsoil existence of hydrogen, the discovery of an extensive hydrogen field covering an estimated area of more than 8 km in diameter in Mali in 2018 helped kickstart the commercial search for natural hydrogen deposits.

The presence of hydrogen in the area was first discovered near the village of Bourakebougou when an old water well that had been drilled in 1987 was plugged and abandoned after an unexpected gas explosion.

The well was unplugged in 2011 and was found to be seeping a gas composed of 98% hydrogen, 1% nitrogen, and 1% methane.

The gas was connected to an engine with internal combustion which then supplied the nearby village with electricity for the first time, bringing much needed light and refrigeration to the remote dwellings for more than seven years before a technical failure. 

The pressure of the gas at the site remains constant today, suggesting a renewal process is occurring rather than a gradually depleting, exhaustible reservoir.

Surface geochemistry indicates that the occurrence of hydrogen seeps extends up to 150 km from the site, according to studies chronicled in the study ‘Discovery of a large accumulation of natural hydrogen in Bourakebougou (Mali)’.

“We may consider already that natural hydrogen accumulations have been clearly demonstrated in Mali, opening a pathway to an industrial exploitation,” the study concluded.

“The cost associated with the exploitation of 1kg of natural hydrogen may be estimated to be two to 10 times smaller than the cost of manufactured hydrogen, rendering this new source of energy quite attractive for the future of our energy consumption.”

By Paul Day